Influenza virus polymerase acidic protein (PA)

Influenza virus polymerase acidic protein (PA) is a key viral enzyme essential for influenza virus RNA transcription and replication. PA functions as part of the heterotrimeric RNA-dependent RNA polymerase complex, alongside PB1 and PB2, and is responsible for the endonuclease activity central to the cap-snatching process, whereby short capped fragments of host pre-mRNAs are cleaved and used to prime viral mRNA synthesis. This protein is highly conserved among influenza A and B viruses, is critical for viral genome replication, and represents a validated antiviral drug target, with inhibitors such as baloxavir directly targeting its enzymatic activity. Its structure and function have been extensively characterized, offering insights for rational drug design and therapeutic intervention strategies. PA’s interaction with other viral and host proteins also makes it crucial for host adaptation and virulence.

Other names

PAPolymerase acidic proteinP3 (Influenza C virus)FluPol PA subunit

Endonuclease inhibition (e.g., by baloxavir, drugs block the cap-snatching activity that is critical for transcription initiation); Disruption of protein-protein interactions (inhibitors blocking PA binding to PB1 may interfere with polymerase assembly and function)